Mode of balancing window-sashes



`ALFRED .'l. CLARK, OF LANCASTER, PESYLVANIA.

MODE 0F BALANCING wINDow-sAsHEs.

Specification of Letters Patent No. 10,957, dated May 23, 1854.

T0 allewlwm t may concern:

Be it known that I, ALFRED T. CLARK, of

the city andcounty of Lancaster and State of Pennsylvania, have invented a `new `and useful Differential VVindo-w-Balance; and I do herebydeclare that the following `is a full, clear,`and eXact description of the same, reference being had to` theaccompanying drawings, forming part of this specification, in which-` e l Figure 1, is a front elevation of` a window framepa portion being bro-ken away to show the cords and pulleys.` Fig. 2, isa vertical transverse section of the.sa1ne,plainly showing the balancing arrangement.

Similar letters of reference in each of the two figures, indicate corresponding parts.

My invention has reference` to a well known arrangement of window sashes wherein the one sash is made to balance the other so that upon lifting the,` lower sash the upper sash descends. By theordinary mode or cord and pulley arrangement of gearing together these sashes, the two sashes move with equal velocities in opposite directions and of course through equal lengths of spaces. This arrangement is objectionable asit does not admit ofthe win` dow being as fully open at the bottom as is frequently desirable in warm weat-her to a` `person sitting at the window and under other circumstances, by reason of the top sash descending below the bottom of the lower sashwhen the latter is raised above a medium height, thereby causing the upper sash to contract or partly close the air or open space formed by the highly raised lower sash.

To `remove this defect is the object of my improvement which consists in so gearing the upper and lower sash together that, while they continue to balance each other, the sashes are made to move at: different velocities or through different lengths of spaces in opposite l directions so that the lower sash may be lifted high, or through a great length of space, while the upper one, descending through a less length of space, will not lapove'r or below the bottom edge of the lower sash, whereby the air or open space formed by the raised lower sash will not be contracted or partly closed by the upper sash, and thus the window `may be opened .wide to the air at the bottom. The means by which I accomplish this improvementconsist of a fixed pulley placed on each side of the window frame at `or near the topportion of the said frame and a traveling pulley or movable sheave placed on each side of the upper sash near the top portion of the said sash, `and two weighted cords attached by their weighted ends to the lower sash, then passingupward over the fixed pulleys,` thence downward under the aforesaid `movable sheaves, and again up ward, andfastened to the top of the window frame, the aforesaid pulleys all revolving on their respective axes. By this arrange ment of cords, movable sheaves and iiXed pulleys, the lower sash is caused to move twice as fast as the upper sash, so that in elevating the `lower sash two feet the upper sash will descend butone foot.` U

Ast-he dierence between the amount of open space, above the sashes, and that below them, is equal to, and results from, the difference between the motion of the upper sash, and that of the lower sashpl have denominated my invention, the differential windowbalance.

To enable others skilled `in the art to make and use my invention, I will proceed to describe its construction and operation.

A, A, represent the window frame; B, the lower sash, and C, the upper sash.

D, D, are the cords connected with the lower sash B, and passing upward over the fixed pulleys, E, E, atthe `top of the framethence downward and around the movable sheaves, F, F, placed on the upper sashthence upward and fastened to the top of the frame, ata, as seen in the drawing, Fig. 2. In order to elevate the lower sash, without moving the upper sash, I attach small weights, H, H, to the lower ends of the cords, D, D, `to keep them stretched, when the cords are relieved of the weight of the sashes. A bolt or catch, I, will sustain the upper sash, when the cords are relieved of the weight of the lower sash. Agroove, G, in each side of the lower sash, allo-ws each `of the small weights, H, H, to remain stationary, when only the lower sash is raised or lowered. Y

Instead of using the small weights, H, H, I can keep the cords stretched, by causing the sheaves, F, F, to move in guides in the sides of the upper sash.

Each of the small weights H, H, is formed` of a screw tube, b, having a nut, c, working upon 1t. The said weightsv serve each, or

" all, of the following purposes, to wit: for

stops for sustaining the lowerV sash, when it is balanced by the upper sash; second, for keeping the cords, D, D, stretched, when they are relieved of the weight of the lower sash, and, third, for adjusting the length of the cords, D, D

A-catch, N, will sustain the lower sash,-

larrangement of the pulleys and sheaves will be seen; also, the manner'in which' the sashes are raised, lowered and balanced. In this view, the red lines show the lower sash raised, and the upper sash lowered-the lower sash being shown raisedy twice the distance the upper sash is lowered; thus plainly illustrating my differential window balance. p t

What l claim as new and useful 1n window sashes wherein the one sash is made to balance the other, and desire to secure by Letters Patent isi Gearing the two sashes together in suc a manner that, while the balance of the sashes, the one by the other, is preserved, a dierential movement is obtained for the two sashes, by means of the fixed and traveling pulleys (E and F) 4with their cords, chains or ropes (D) arranged and operating, together with the sashes, substantially as specified, so that, on raising the lower or one sash through a given length of space, the other or upper sash is caused to descend through a less length of space, whereby a wider opening or air space may be procured for the window at its bottom than is obtainable byA the ordinary arrangement herein referred to and described in which the sashes balancing each other are made to Vmove with equal velocities and the top sash thereby caused to contract or partly close the open air space at the bottom formed by the highly raised lower sash.

, ALFRED T. CLARK. Witnesses:

JOHN K..SuoKERs, I. BUYERS FREELANDY. 

